Hi Niz,
I'm glad you feel you're coping better, but I can also relate to the low times. My mum also has depression and anxiety, and she told me, "There will be good days and there will be bad days". I think, knowing that some days will be bad, does help - it's not you failing or necessarily getting worse, we all have good and bad days.
It is just really tough having a "bad day" or a low day, when you are fighting depression too.
I recommend using this site, I also know the people here aren't the cure, but I have found great relief in being able to express how I'm feeling, working through my illness, and also the friendship and compassion that people on this site have shown me, has been a great comfort.
I was also at a point of thinking there is no light at the end of the tunnel, but I have also consequently felt positive and hopeful about my recovery.
If you feel like you are sinking, then you should perhaps go see your GP again because maybe you need a higher dose of meds.
If it ever gets really bad, please call the Dr or a friend, or Samaritans, who I really recommend. Their number is 08457 90 90 90. I have used them a few times and they're wonderful, just to talk about things when I feel hopeless.
Look after yourself Niz, try to take good care of yourself. Let us know how you're doing.